Lubricants for inhibiting silver wear



United States Patent 3,252,912 LUBPJCANTS FQRINHIBITING SILVER WEAR Edwin L. De Young, Milwaukee, Win, and Roger W.

Watson, Highland, Ind., assignors to Standard Oil Comparry, Chicago, 111., a corporation of Indiana No Drawing. Original application Jan. 16, 1962, Ser. No. 167,225. Divided and this application Jan. 26, 1965, Ser. No. 438,812

5 Claims. (Cl. 25249.6)

This is a division of application Serial No. 167,225, filed January 16, 1962.

This invention relates to certain silicon-containing compositions useful as anti-wear additives in lubricants normally tending to cause excessive wear of silver bearings.

Many hydrocarbon oils are compounded with various sulfur compounds which act as oxidation or corrosion inhibitors. Sulfur compounds, however, promote high wear in silver and silver-containing bearings and bushings.

It has now been discovered that such excessive Wear of silver bearings may be inhibited substantially by incorporating into hydrocarbon lubricating oils which tend to promotewear a minor amount of a compound having the structure wherein the Rs are selected from the group consisting of hydrogen atoms and alkyl radicals taken in sutlicient number to satisfy the valence requirements of the benzene rings.

Hydrocarbon lubricant oils which may be improved with respect to their silver wear characteristics according to the invention may be any of the natural 'or synthetic hydrocarbon oils of suitable viscosity range, e.g., from about SSU viscosity at 100 F. to about 3,000 SSU at 210 F. These may be derived from natural, i.e., mineral, sources such as petroleum oils, or may be composed in whole or in part of synthetic hydrocarbon, as for example the polybutenes. The oils may contain any of the ingredients normally incorporated for the purpose of improving detergency, oxidation resistance, lubricity, extreme pressure characteristics, rust inhibition, etc. Ordinarily, it is considered that sulfur-containing materials tend to be most deleterious from the standpoint of silver wear, and accordingly it is with sulfur-containing hydrocarbon oils that the inventive additives have their most attractive utility.

By way of illustration, sulfur-containing additives nor .mally present in lubricant oils include the sulfurized terpenes, sulfurized tall oil, octyl polysul-fide, various reaction products of phosphorus pentasulfide with olefinic hydrocarbons, metal sulfonates, sulfochlorinated olefins, etc.

The inventive additives may be prepared simply by reacting the corresponding catechol with silicon disulfide under anhydrous conditions, maintaining a suflicient temperature, and for sufficient time, to effect substantial reaction. No further treatment need be employed.

Suitable catechols include unsubstituted catechol and the various alkyl substituted (monoalkyl and di-alkyl preferably) catechols, especially those Where the alkyl group contains from 4 to 30 carbon atoms, optimally from about 6 to about 24 carbon atoms. Illustrative of the various alkyl cathechols are butyl catechol, nonyl catechol, dinonyl catechol, dodecyl catechol, tetradecyl catechol, hexadecyl catechol, and eicosadecyl catechol, in each case with the alkyl group or groups being either straight or branched chain.

3,252,912 Patented May 24, 1966 ice The inventive additive may be incorporated into hydrocarbon lubricant oils in a wide range of concentrations, with the optimum concentration depending upon the initial wear characteristics of the oil, the nature of Wearproimoting additives in the oil, and the extent of inhibition desired. In general, concentrations of as little as 0.05 weight percent, or even less, up to as much as 3 percent by weight, or even more, will provide suitable inhibition. However, for any particular lubricant composition it is a simple matter to conduct tests which will provide a quantitative or semi-quantitative indication of the requisite amount of inhibitor necessary.

Illustrative embodiments of the invention are given in the following examples, which are provided for illustration only. Hence they are not to be considered wholly definitive with respect to scope or conditions.

Example 1 This example illustrates the preparation and testing of a compound according to the invention which is prepared from dodecyl catechol and silicon disulfide.

To 4.6 grams (0.05 mol) of silicon disulfide is added 25 grams (0.1 mol) of dodecyl catechol. The mixture is heated for two hours at C. until evolution of hydrogen sulfide ceases. At the conclusion of reaction, the material is cooled; a sample analyzes 2.3 weight present silicon.

In order to demonstrate the remarkable effectiveness of this additive with respect to its ability to inhibit silver wear, comparative tests are conducted with the Falex tester, using a silver ball on a steel surface. The Falex test is described in Journ. Inst. Pet., 32, April 1946. The base oil in each case is a 73 viscosity index mineral lubricant, containing 2.8 percent detergent (barium neutralized and hydrolyzed reaction product of phosphorus pentasul'fide and a hydrocarbon), 1.0 weight percent calcium phenate, and 0.2 percent sulfurized terpene. In the absence of any of the inventive inhibitor, the weight loss is 275 milligrams; with only 0.5 weight percent of the inventive inhibitor, the Weight loss is 6.5 and 12.8 milligrams in duplicate tests.

Example 2 Utilizing the same molar quantities as for Example 1, an inhibitor is prepared from unsubstituted catechol. At a concentration of 0.05 weight percent in the abovedescribed base oil, excellent silver wear inhibition is demonstrated.

Example 3 Repeating Example 1 but substituting the same molar quantity of octyl catechol, an additive is obtained which, at 0.2 weight percent concentration in the above-described base oil, displays exceptional silver wear inhibition.

Example 4 In this example the preparation of Example 1 is repeated, except that an equivalent molar quantity of 50:50 mixture of octadecyl and eicosyl catechol is employed. At a 2.0 weight percent concentration in the abovedescribed lubricant oil, outstanding silver wear inhibition is obtained.

Thus it is evident that there has been provided, in accordance with the invention, an outstanding additive for improving the silver Wear characteristics of hydrocarbon lubricant oils which normally tend to cause such wear. While the invention has been described in conjunction with specific embodiments thereof, particularly in connection with organic sulfur containing mineral lubricants, it is evident that many alternatives, modifications, and variations of the invention will occur to those skilled in the art in light of the foregoing description. Accordingly,

it is intended to embrace all such alternatives, modifications, and variations as fall within the spirit and broad scope of the appended claims.

- We claim:

1. A hydrocarbon lubricating oil containing a sulfurcontaining additive causing silver wear, and about 0.05-3 weight .percent of a compound having the structure where R and R are each C alkyl, and n and m are each 0-4.

4 2. The lubricating oil of claim 1 wherein n and m are each 1. v

3. The lubricating oil of claim 2 wherein R and R are each dodecyl. v

4. The lubricating oil of claim 2 wherein R and R are each octyl.

5. The lubricating oil of claim 1 Where n and m are each 0.

References Cited by the Examiner UNITED STATES PATENTS 9/1955 Foehr DANIEL E. WYMAN, Primary Examiner.

P. P. GARVIN, Assistant Examiner. 

1. A HYDROCARBON LUBRICATING OIL CONTAINNG A SULFURCONTAINING ADDITIVE CAUSING SILVER WEAR, AND ABOUT 0.05-3 WEIGHT PERCENT OF A COMPOUND HAVING THE STRUCTURE 